The Titus Tunnel, Turkeysupposedly built in the Roman periods, but probably not at all because its style belongs to a completely different older periods (plus there are ruins in that old style in the vicinity)

La Maná, Ecuador80 meters high wall, unexplored, seems to part of an entire complex, according to legends these are the ruins of the buildings of giants

Longyou Grottoes, Chinathe machine tool marks are clearly visible, the complex is so large that the full mountain is practically hollow

Castles of Eğil, Turkeyabsolutely amazing, the core of the rock carved castle is still standing, a living piece of fairy tale